Underground Mine and Method of Mining

ABSTRACT

A method of underground mining includes mining material using a continuous miner to form at least one set of entries comprising a plurality of entries. A plurality of crosscuts extend between and connect the entries. A plurality of pillars are defined by the entries and crosscuts. The entries and crosscuts define a passage having a roof, a floor, and sidewalls. The pillars at least in part are adapted to prevent the roof of the passage from collapsing. Roof bolts are installed in the roof of the passage. Material is mined from the sidewalls of the passage with the continuous miner to form perimeter cuts extending outwardly from the passage. The perimeter cuts are free of roof bolts. At least approximately 30 percent of the material mined from within the set of entries is derived from the unbolted perimeter cuts.

CROSS-REFERENCE TO RELATED APPLICATION

This divisional patent application claims priority from U.S. patentapplication Ser. No. 11/339,761 filed on Jan. 25, 2006, the entirety ofwhich is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

The present invention generally relates to an underground mine and amethod of mining and more particularly to employing ventilationconfigurations to permit more rapid extraction of material.

The need for properly ventilating underground mines, such as undergroundcoal mines, has long been recognized and serves two key purposes: 1) todilute and remove potentially harmful gases (e.g., methane, carbondioxide) and dust; and 2) to provide breathable air to the workers inthe mine. Accordingly, fresh outside air is circulated along acirculation path through the mine to move gases and dust away from theface of the mine (i.e., the exposed area of a seam from which coal orore is being extracted), and to bring breathable air to the areas of themine in which workers may be present.

After the ventilation air passes the face of the mine it is referred toas return air. Return air carries any harmful gases and/or dust awayfrom the face of the mine and is vented to a location outside of themine. Mining regulations prohibit mine workers from working in thereturn air. This prevents workers from potentially being exposed to anyharmful gases or dust that may be present in the return air. As aresult, all mine workers prefer to be upstream of any extractionprocesses that are occurring at the mine face.

Accordingly, the circulation path of the ventilation air through themine plays a critical role in determining the extraction process. Coaland other types of ore are typically mined using mechanical miningequipment, for example, a continuous miner. Since mine workers prefer tobe upstream of the continuous miner, conventional ventilationtechniques, which are described below in more detail, substantiallylimit the efficiencies of operating an underground mine.

SUMMARY OF THE INVENTION

One aspect of the present invention is directed to a method ofunderground mining. The method generally comprises mining material usinga continuous miner to form at least one set of entries comprising aplurality of entries, a plurality of crosscuts extending between andconnecting the entries, and a plurality of pillars defined by theentries and crosscuts. The entries and crosscuts define a passage havinga roof, a floor, and sidewalls. Roof bolts are installed in the roof ofthe passage. Material is mined from the sidewalls of the passage withthe continuous miner to form perimeter cuts extending outwardly from thepassage. The perimeter cuts are free of roof bolts. At leastapproximately 30 percent of the material is mined from within the set ofentries being derived from the unbolted perimeter cuts.

Other objects and features will be in part apparent and in part pointedout hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic showing part of an underground mine, portions ofthe mine are shown in phantom indicating areas that have not yet beenmined;

FIG. 1A is an enlarged detail of the circumscribed portion of FIG. 1;

FIG. 1B is an enlarged detail of the circumscribed portion of FIG. 1;

FIG. 2 is a schematic of the part of the underground mine showing aknown ventilation configuration;

FIG. 2A is an enlarged detail of the circumscribed portion of FIG. 2;

FIG. 3 is a schematic of the part of the underground mine showinganother known ventilation configuration;

FIG. 3A is an enlarged detail of the circumscribed portion of FIG. 3;

FIG. 4 is a schematic of part of an underground mine showing oneventilation configuration in accordance with the present invention;

FIG. 4A is an enlarged detail of the circumscribed portion of FIG. 4;

FIG. 5 is a schematic of the part of the underground mine showing asecond ventilation configuration in accordance with the presentinvention;

FIG. 5A is an enlarged detail of the circumscribed portion of FIG. 5;

FIG. 6 is a schematic showing part of an underground mine having sets ofperimeter wall entries;

FIG. 6A is an enlarged detail of the circumscribed portion of FIG. 6;

FIG. 7 is a schematic of the part of the underground mine of FIG. 6showing a third ventilation configuration in accordance with the presentinvention;

FIG. 7A is an enlarged detail of the circumscribed portion of FIG. 7;

FIG. 8 is a schematic of the part of the underground mine of FIG. 6showing a fourth ventilation configuration in accordance with thepresent invention;

FIG. 8A is an enlarged detail of the circumscribed portion of FIG. 8;

FIG. 9 is a schematic of part of an underground mine showing yet anotherventilation configuration in accordance with the present invention;

FIG. 9A is an enlarged detail of the circumscribed portion of FIG. 9;

FIG. 10 is a schematic of the part of the underground mine of FIG. 10showing a still another ventilation configuration in accordance with thepresent invention; and

FIG. 10A is an enlarged detail of the circumscribed portion of FIG. 10.

Corresponding reference characters indicate corresponding partsthroughout the drawings.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings and in particularly to FIG. 1. FIG. 1shows a portion of an underground mine advanced into a coal seamincluding a panel development, indicated generally at 10, extendingoutwardly from a set of main entries, indicated generally at 12. Aportion of the coal mine is shown in phantom to indicate areas that areplanned to be mined but have not yet been mined. While the invention isdescribed herein with reference to a coal mine, it is understood thatthe present invention can be used in other types of underground mines.

The set of main entries 12 includes main entries 14 and main crosscuts16 extending between the main entries. The main entries 14 and maincrosscuts 16 cooperate to define a plurality of pillars 18. The set ofmain entries 12 is shown in FIG. 1 truncated as it is understood thatthe set of main entries can include any number of main entries 14 andany number of crosscuts 16. The main entries 14 can extend indefinitely.In some mines, the main entries 14 extend for a mile or more.

The main entries 14 are tunnels formed during the coal extractionprocess that serve as passages in the mine for subsequent miningoperations. In short, they are the main arteries used to transport mineworkers, equipment, and/or coal into and out of the underground mine. Inthe illustrated configuration, the passages defined by both the mainentries 14 and the main crosscuts 16 are approximately 20 feet wide. Butthe width of the passages can be greater or less than that illustrated.The width of the passages defined by the main entries 14 can also begreater or less than the width of the passages defined by the maincrosscuts 16.

The set of main entries 12 can be divided into sets of sub-main entries(not shown), which are branches extending from the set of main entries,to access a portion of the mine. In short, the set of main entries 12can be used to access all or most of the mine whereas the set ofsub-main entries feed off of the set of main entries and are used toaccess only a portion of the mine. The distinction between sets of mainentries and sets of sub-main entries is not germane to the presentinvention. Thus, sets of main entries and sets of sub-main entries aregrouped herein simply as sets of main entries 12.

The pillars 18 are portions of the mined coal seam that are left inplace to keep the passages open during mining and to prevent subsidenceof the overlying surface. The pillars 18 prevent the roof of the minefrom collapsing because of the weight of the overburden. For example,the pillars 18 defined by the main entries 14 and main crosscuts 16 inthe illustrated configuration are approximately 60 feet by 60 feet. Thepillars 18 are about 20 feet apart in both a longitudinal direction anda lateral direction. It is understood that the pillar size, shape, andspacing can be different.

Referring to FIG. 1A, roof supports, such as roof bolts 20, aretypically installed in the roof in the passages defined by the mainentries 14 and the crosscuts 16 (i.e., between the pillars 18) to assistin supporting the roof of the mine. Roof bolts 20 are long steel bolts(e.g., 4 feet) driven into the overburden defining the roof of the mineto support the roof. Basically, the bolts 20 fasten portions of theoverburden together and stabilize the roof. Installing roof bolts 20 isboth costly and dangerous as it requires mine workers to enter portionsof the mine that are supported only by the pillars 18. Other roofsupports (not shown), such as timbers, posts, and jacks, may also beused to support the mine roof.

Referring again to FIG. 1, extending outwardly from the set of mainentries 12 is the panel development 10, which includes a set of panelentries, indicated generally at 22, and a plurality of sets of rooms,indicated generally at 33. In the illustrated configuration, the set ofpanel entries 22 comprises seven panel entries 24, and a plurality ofpanel crosscuts 26 forming passages through the panel development 10.The length of the panel entries 24, like the main entries 14, isindefinite but is commonly less than the distance of the main entries.For example, the panel entries 24 of the illustrated configuration,including the portions shown in phantom, are approximately 2,000 feetwhen fully advanced. Roof bolts 20 are installed in the roof of thepassages defined by the panel entries 24 and panel crosscuts 26 in thesame manner as described above with respect to the set of main entries12.

The panel entries 24 and panel crosscut 26 cooperatively define aplurality of panel pillars 28. The panel pillars 28 in the illustratedpanel development 10 are the same size as those in the set of mainentries 12. It is understood, however, that the panel pillars 28 can besmaller or larger than the main pillars 18. It is also understood thatthe panel pillars 28 can have different shapes and sizes, and accountfor more or less of the coal seam than shown herein.

With reference still to FIG. 1, five of the panel entries 24 areinterior entries B-F having panel pillars 28 on both sides of the panelentries and the remaining two panel entries are exterior entries A, G.That is, they have panel pillars 28 on one side and a longitudinalsidewall 30 defined by the coal seam on the opposite side. In addition,one of the panel crosscuts 26 (i.e., the crosscut at the furthest extentof the panel development) defines an end wall 32 of the paneldevelopment 10. The other panel crosscuts 26 are interior crosscutshaving panel pillars 28 on both sides.

Extending outwardly from the sidewall 30 of the panel entries 24 are theplurality of sets of rooms 33 comprising rooms 34, crosscuts 36connecting the rooms, and pillars 38 defined by the rooms and thecrosscuts. Sixteen sets of rooms 33 are shown extending outwardly fromthe panel entries 24 but it is understood that more or fewer rooms canbe advanced off of the panel entries 24. Moreover, eight of the sixteensets of rooms 33 extend to the left of the panel entries 24 (as view inFIG. 1) and eight sets of rooms extend to the right. It is understood,however, that the number of rooms extending to the right and left of thepanel entries 24 can be different. While the sets of rooms 33 are shownextending outwardly from the set of panel entries 22 it is understoodthat the sets of rooms can extend outwardly from the set of main entries12.

A portion of the panel development 10 illustrated in FIG. 1 is shown inphantom to indicate portions of the mine planned to be mined but whichhave not yet been mined. The portions of the panel development 10 shownin solid line indicated portions of the mine that have already beenmined. The panel development 10 could have been mined to its currentstate by advancing the set of panel entries 22 to a location slightlybeyond where a first set of rooms 33′ have been advanced outwardly fromthe set of panel entries. The first set of rooms 33′ extending outwardlyfrom the set of panel entries 22 to the left as viewed in FIG. 1 werefully mined. The set of panel entries 22 were then advanced to locationslightly beyond where a second set of rooms 33′ were advanced outwardlyfrom the set of panel entries. The second set of rooms 33″ on the leftside of set of panel entries were fully mined and then the set of panelentries were advanced to a location beyond the next set of rooms 33 asshown in FIG. 1. The process of advancing the set of panel entries 22and completing sets of rooms 33 is continued until the set of panelentries is fully advanced and all of the rooms on the left side of theset of panel entries are fully mined as shown in phantom in FIG. 1.Next, the rooms on the right side of the set of panel entries 22 arecompleted starting with the set of rooms 33 closest to the end wall 32and ending with the set of rooms closest the set of main entries 12.

The number of rooms 34 in each set of rooms 33 can be different. Asillustrated, most of the sets of rooms 33 have four rooms 34 but it isunderstood that the sets of rooms can have more or fewer rooms. Forexample, the first set of rooms 33′ has only two rooms H, I. The secondset of rooms 33″ has three rooms J, K, L. In the illustratedconfiguration, the rooms 34 extended outwardly from the sidewalls 30 ofthe panel 24 approximately 300 feet. The rooms 34 can be extended up toa regulatory maximum distance of 600 feet or can be shorter than 300feet.

The room pillars 38 are smaller than the main pillars 18 and the panelpillars 28. Thus, more coal is extracted from the coal seam in the setsof rooms 33 than from the set of main entries 12 or set of panel entries22. More particularly, the room pillars 38 are approximately 30 feet by40 feet. The room pillars 38, like the main pillars 18 and the panelpillars 28, are spaced apart approximately 20 feet in both thelongitudinal and lateral directions. It is understood that the roompillars 38 can have different sizes, shapes, and spacing than thoseillustrated. The roof of the mine between the room pillars 28 (i.e., inthe passages defined by the rooms 34 and room crosscuts 36) is supportedusing roof supports (e.g., roof bolts 20).

In the illustrated configuration, coal is extracted from longitudinalsidewalls 40 and an end wall 42 of each set of rooms 33. The void in thecoal seam created by extracting coal from the longitudinal sidewall 40or end wall 42 is referred to as a perimeter cut 44. The perimeter cuts44 formed in the end wall 42 and sidewalls 42 are generally orthogonalto the end wall and sidewalls, respectively. In the illustrated mine,the cuts 44 are approximately 20 feet wide and approximately 40 feetlong but can have other widths and lengths. The coal extracted from theperimeter cuts 44 account for about 20 percent to about 23 percent ofthe total coal extracted from each of the sets of rooms 33. Roof bolts20 are preferably not used within the cut 44.

The height of the perimeter cuts 44 corresponds generally to thethickness of the coal seam. In the set of main entries 12, set of panelentries 22, and sets of rooms 33 (i.e., rooms 34 and room crosscuts 36),on the other hand, rock overlying and/or underlying the coal seam isoften removed to provide sufficient clearance for allowing equipment andworkers to pass through the entries. The removal of rock significantlyincreases production costs by allocating mining resources and efforts tothe removal a rock, which is a liability and not a commodity, like thecoal. Moreover, the overlying and underlying rock is typically harderand heavier than the coal, making it more difficult to mine and handle.Furthermore, the rock is often dumped in a gob pile, which has to bemanaged and takes up substantial land space.

During the mining process, a continuous miner 46 extracts coal and/orrock from the face of the mine. The extracted coal and/or rock istransported from the continuous miner 46 to a conveyor belt 48 usingbattery-powered haulers (not shown). The conveyor belt 48 transfers theextracted materials to the surface. Typically, the conveyor 48 runsthrough the set of main entries 12 and set of panel entries 22 to alocation in relatively close proximity to the face of the mine so thatas coal is extracted it needs to be transported by one of the haulersonly a short distance before being loaded onto the conveyor belt. Thedistance between the face of the mine and conveyor belt 48 is oftenminimized to keep the hauler trips short. The conveyor belt 48 istypically not extended into the sets of rooms 33 because of therelatively short length of the rooms 34.

As illustrated in FIG. 1B, to advance the set of main entries 12, set ofpanel entries 22, or rooms 34 coal is extracted a short distance (e.g.,between 10 feet and 40 feet) using the continuous miner 46 in one of theentries or rooms to form a short, unsupported area. The continuous miner46 is then moved to an adjacent entry 12, 22 or room 34 to do the same.While the continuous miner 46 is extracting coal from the adjacent entry12, 22 or room 34, mine workers install roof bolts 20 in the previouslyextracted area. This alternating process is continued until the entry12, 22 or room 34 is advanced the desired distance. For example, in FIG.1B, rooms P, O, N have been advanced approximately 20 feet from thenearest crosscut 36 using the continuous miner 46 and roof bolts 20 havebeen installed in two of the rooms P, O. Roof bolts 20 are beinginstalled in the third room N, which is shown as completely installed inFIGS. 2A and 3A. Referring again to FIG. 1B, the continuous miner 46 isshown advancing room M. The continuous miner alternates mining the roomsP-M until the rooms are advanced beyond where one of the room crosscuts36 is to be formed, and then the crosscut is made and roof bolted. Afterthe crosscut 36 is completed, the rooms P-M are advanced until the nextcrosscut 36 needs to be made. This process is continued until the set ofrooms 33 are fully advanced. Once one of the sets of rooms 33 is fullyadvanced, the perimeter cuts 44 are made using the continuous miner 46as shown in FIG. 2.

The mining operation is carefully planned to ensure that gas ignitionsare prevented and the mine workers have fresh air to breathe and are notexposed to any potential harmful gases or dust that may be produced atthe face of the mine. As illustrated in FIG. 1, this is done bydirecting intake air to move along a predetermined air circulationpathway through the mine.

In FIG. 1, which illustrates a conventional ventilation technique, threepanel entries E-G are used to supply fresh air (commonly called “intakeair”) to the mine face and two of the panel entries A, B are used as airreturns for exhausting any potential gases (e.g., methane) and/or dustfrom the area of the mine being mined by the continuous miner 46 (i.e.,the face of the mine). Two of the interior panel entries C, D areneutral and are used for hauling coal from the mine via the conveyorbelt 48 and for transporting mine workers into and out of the mine.

The panel entries E-G with intake air are separated from the neutralpanel entries C, D and the neutral panel entries are separated from thepanel entries A, B with return air using barriers. The barriers are usedto direct air flow in a desired circulation path through the mine. Theillustrated barriers include a plurality of stoppings 50 and a pluralityof curtains 52. Stoppings 50, which are typically concrete block ormetal panels, and curtains 52, which are typically sheet material (e.g.,plastic, cloth), are extended between the main pillars 18, the panelpillars 28, and/or the room pillars 38 to direct air flow through theset of main entries 12, set of panel entries 22, and/or one of the setsof rooms 33, respectively. Typically, only curtains are used in the setsof rooms 33.

In the configuration illustrated in FIGS. 1 and 2, intake air isdirected using curtains 52 through the main entries 14 into the panelentries 24 and into one of the sets of the rooms 33 so that the intakeair passes the face of the mine. The path of the intake air is shown inthe Figures using arrows. Since each of the sets of rooms 33 are minedand vented in substantially the same way, only the mining and venting ofonly one set of rooms is described.

In the illustrated configuration, intake air enters the paneldevelopment 10 and is directed through panel entries E-G using curtains52. Curtains are also used to direct the intake air through one of thepanel crosscuts 26 and into one of the sets of rooms 33. The intake airis directed using curtains 52 through room P and through one of the roomcrosscuts 36 where it passes the continuous miner 46 (i.e., the face ofthe mine) thereby entraining any potential harmful gases or dust. Afterpassing the face of the mine, the air is referred to as return air andis represented in the drawings by two-headed arrows. The return airexits through room M and into panel entries A, B where it is directedusing stoppings 50 to exit the panel development 10 into the set of mainentries 12 and then to a vent location (not shown) located outside ofthe mine. Air is directed through the circulation pathway using a fan(not shown). The fan can be used to either force or draw air through thecirculation pathway.

As mentioned above, mining regulations prohibit mining activities in thereturn air. As a result, only one continuous miner 46 can operate in theset of rooms 33 when the air circulation technique illustrated in FIGS.1 and 2 is used.

A second continuous miner 46 can be used if the ventilation air iscirculated through the mine as shown in FIG. 3. In this knownventilation configuration (sometimes referred to as “fishtailing”)intake air is directed using both stoppings 50 and curtains 52 to flowthrough the main entries 14, through two of the interior panel entriesE, F and is split into two intake air flows within the set of panelentries 22. As a result of the split intake air flow, sets of rooms 33on opposite sides of the set of panel entries 22 can be supplied intakeair. As a result, continuous miners 46 can be used or other miningoperations can be preformed in each of the sets of rooms 33 with intakeair. In the illustrated configurations, two continuous miners 46 arebeing used to perform perimeter cuts 44. After the intake air passes thecontinuous miners 46 and becomes return air, the return air flowsthrough one of the rooms M, M′ in each of the sets of rooms 33 to whichintake air was directed. After leaving the set of rooms 33, the returnair flows through the panel entries A, B located adjacent the left sideof the set of panel entries 22 (as viewed in FIG. 3), or through theexterior panel entry G located adjacent the right side of the set ofpanel entries. Two of the interior panel entries C, D are neutral andcontain the conveyor belt 48 for transferring coal from the near theface of the mine to the surface. As compared to the ventilationconfiguration illustrated in FIGS. 1 and 2, the ventilationconfiguration shown in FIG. 3 requires additional ventilation controls(i.e., more stoppings 50 and/or curtains 52) because two air returns areused instead of one.

FIG. 4 shows a panel development 110 that is similar to the paneldevelopment 10 described above with reference to FIGS. 1-3. Morespecifically, the set of main entries 112 and the set of panel entries122 are substantially the same as the set of main entries 12 and set ofpanel entries 22, respectively. Corresponding parts of the set of mainentries 112 and set of panel entries 122 are indicated by the samereference numbers used in FIGS. 1-3 plus “100”.

Extending outwardly from each of the sidewalls 130 of the set of panelentries 122 are numerous sets of perimeter wall entries 133 comprisingperimeter wall entries 134, perimeter wall crosscuts 136 connecting theperimeter wall entries 134, and perimeter wall pillars 138 defined bythe perimeter wall entries and the perimeter wall crosscuts. As before,the parts shown in phantom indicate proposed excavations whereas solidlines indicate areas already mined. Sixteen sets of perimeter wallentries 133 are shown extending outwardly from the set of panel entries122 but it is understood that more or fewer perimeter wall entries canbe advanced off of the set of panel entries. Moreover, eight of thesixteen sets of perimeter wall entries 133 extend to the left of the setof panel entries 122 (as view in FIG. 4) and eight sets of perimeterwall entries extend to the right. It is understood, however, that thenumber of perimeter wall entries extending to the right and left of theset of panel entries 122 can be different. While the sets of perimeterwall entries 133 are shown extending outwardly from the set of panelentries 122 it is understood that the sets of perimeter wall entries canextend outwardly from the set of main entries 112.

The number of perimeter wall entries 134 in each set of perimeter wallentries 133 can be different. As illustrated, most of the sets ofperimeter wall entries 133 have four perimeter wall entries 134 but itis understood that the sets of perimeter wall entries can have more orfewer perimeter wall entries. For example, the first set of perimeterwall entries 133′ has only two perimeter wall entries H, I. The secondset of perimeter wall entries 133″ has three perimeter wall entries J,K, L. In the illustrated configuration, the perimeter wall entries 133extended outwardly from the sidewalls 130 of the set of panel entries122 approximately 300 feet. The set of perimeter wall entries 133 can beextend well beyond 300 feet (i.e., 1,000 feet or more) or can be shorterthan 300 feet.

The perimeter wall pillars 138 are smaller than the main pillars 118 andthe panel pillars 128. Thus, more coal is extracted from the coal seamin the sets of perimeter wall entries 133 than from the set of mainentries 112 or set of panel entries 122. More particularly, theperimeter wall pillars 138 are approximately 30 feet by 40 feet. Theperimeter wall entries pillars 138, like the main pillars 118 and thepanel pillars 128, are spaced apart approximately 20 feet in both thelongitudinal and lateral directions. It is understood that the perimeterwall pillars 138 can have different sizes, shapes, and spacing thanthose illustrated. The roof of the mine between the perimeter wallpillars 128 (i.e., in the passages defined by the perimeter wall entries134 and perimeter wall crosscuts 136) is supported using roof supports(e.g., roof bolts 120).

In the illustrated configuration, coal is extracted from longitudinalsidewalls 140 and an end wall 142 of each set of perimeter wall entries133. The void in the coal seam created by extracting coal from thelongitudinal sidewall 140 or end wall 142 is referred to as a perimetercut 144. The perimeter cuts 144 formed in the end wall 142 adjacent theperimeter wall entries 134 are generally perpendicular to the end wallwhereas the cuts formed in the end wall between the perimeter wallentries and in the sidewalls 140 are generally oblique to the end walland sidewalls, respectively. The perimeter cuts 144 are formed thismanner for convenience in using the mining equipment. The continuousminers 146 can more quickly mine the perimeter cut 144 when it is angledwith respect to the end wall 142 and sidewalls 140 than when it is at aright angle. The angle between the perimeter cuts 144 and the sidewalls140 and/or end wall 142 can be different than those shown. In theillustrated mine, the perimeter cuts 144 are approximately 20 feet wideand approximately 40 feet long but can have other widths and lengths.The height of the perimeter cuts 144 corresponds generally to thethickness of the coal seam. Roof bolts 120 are preferably not usedwithin the cut 144.

A mine ventilation system in accordance with the presence invention isshown in FIGS. 4 and 4A wherein two continuous miners 146 can be used inthe same set of perimeter wall entries 133 while making the perimetercuts 144 into the sidewalls 140 or end walls 142 of the set of perimeterwall entries. Being able to operate two continuous miners in the sameset of perimeter wall entries 133 as compared to one continuous miner isa significant advantage in the art of mining. For one, the rate at whichthe coal can be extracted can be significantly increased.

As illustrated in FIG. 4, intake air is directed using curtains 152through the main entries 114 into the panel entries E-G and then intoone of the sets of perimeter wall entries 133 so that the intake airpasses the face of the mine. The intake air is directed through at leasttwo of the perimeter wall entries M, P. The other two perimeter wallentries N, 0 in this configuration are neutral. However, intake aircould be supplied to all four of the perimeter wall entries 134. Theflow rate of the intake air can be regulated using the curtains 152 sothat the flow rate is equal in each of the perimeter wall entries 134having intake air supplied thereto. The flow rate could also beregulated so that it is different in one or more of the perimeter wallentries 134. One way to regulate the flow rate of the intake air is topartially open one or more of the curtains 152.

The intake air is directed past the two continuous miners 146 (i.e., theface of the mine) thereby entraining any potential harmful gases ordust. After passing the face of the mine, the return air, is directedout of the set of perimeter wall entries 133 through a bleed pathway 154to one or more of the previously mined sets of perimeter wall entries133′, 133″. It is understood that more than one bleed pathway 154 couldbe used. The return air then flows out of the set(s) of perimeter wallentries 133′, 133″ feed by the bleed pathway 154, through the panelentries A, B and through the main entries 114 to the vent location (notshown) located outside of the mine.

In the configuration illustrated in FIG. 4A, the perimeter cuts 144 inthe end wall 142 are identified as EW1-EW10, and the perimeter cuts inthe sidewalls 140 are identified as SW1-SW7 and SW1′-SW7′. Perimetercuts EW1-EW10, SW1 and SW1′ and the bleed pathway 154 have already beencompleted and the continuous miners 146 are shown mining perimeter cutsSW2 and SW2′. The bleed pathway 154 was completed first followed by theperimeter cuts EW1-EW10 in the end wall 142 by starting in perimeter cutEW1 and working in consecutive order toward perimeter cut EW10 using oneof the continuous miners 146. Once the continuous miner advanced beyondperimeter cut EW5, the second continuous miner 146 began on perimetercut SW1. Perimeter cuts SW1-SW7 and SW1′ and SW7′ are also advance inconsecutive order being with SW1 and SW1′.

FIG. 5 shows another configuration wherein four continuous miners 146can be used to make perimeter cuts 44 within two sets of perimeter wallentries 133. Intake air is directed using both stoppings 150 andcurtains 152 to flow through the main entries 114, through panel entriesE, F and is split into two intake air flows within the set of panelentries 122. As a result of the split, one or more sets of perimeterwall entries 133 on each side of the set of panel entries 122 can besupplied intake air. The illustrated configuration shows one set ofperimeter wall entries 133 located on each side of the set of panelentries 122 being supplied intake air. The intake air is directedthrough at least two of the perimeter wall entries P, P′, M, M′ in eachset of perimeter wall entries 133. The intake air is directed past allfour continuous miners 146 (i.e., the face of the mine) therebyentraining any potential harmful gases or dust. After passing the faceof the mine, the return air, is directed out of each set of perimeterwall entries 133 through a bleed pathway 154 to one or more previouslymined sets of perimeter wall entries. The return air flows out of thepreviously mined sets of perimeter wall entries 133, through arespective one of two exterior panel entries A, G. One of the exteriorpanel entries A is located adjacent the left side of the set of panelentries 22 (as viewed in FIG. 5), and the other exterior panel entry Gis located adjacent the right side of the set of panel entries.

FIG. 6 shows multiple sets of perimeter wall entries, indicatedgenerally at 162, that are substantially longer than the sets ofperimeter wall entries 133 shown in FIGS. 4-5A. Each set of perimeterwall entries 162 comprises perimeter wall entries 164, perimeter wallcrosscuts 166 connecting the perimeter wall entries, and pillars 168defined by the perimeter wall entries and the perimeter wall crosscuts.In the illustrated configuration, the perimeter wall entries 164 extendoutwardly from the sidewalls 130 of the panel 124 approximately 540feet. However, the perimeter wall entries 164 can extend over severalthousand feet or more.

FIGS. 6 and 6A illustrate how the sets of perimeter wall entries 162 areadvanced. As shown only one of the continuous miners 146 is being usedto mine. Coal is extracted a short distance (e.g., between 10 feet and40 feet) using the continuous miner 146 in one of the perimeter wallentries to form a short, unsupported area, such as is shown in perimeterwall entries P, O. The continuous miner 146 is then moved to theadjacent perimeter wall entry N to do the same. While the continuousminer 146 is extracting coal from the adjacent perimeter wall entry N,mine workers can install roof bolts 20 in the previously mine perimeterwall entries P, O. This alternating process is continued until the setof perimeter wall entries 162 are advanced to the desired distance. Asecond continuous miner 146 is shown idle. It is understood, however,that only one continuous miner 146 can be used or that the twocontinuous miners can alternate between mining and idling while the setof perimeter wall entries 162 is being advanced. This alternatingprocess is continued until the set of perimeter wall entries 162 isfully developed.

While the perimeter wall entries 164 are being advanced, a conveyor belt148 is extended into one of the perimeter wall entries O, which isneutral, so that as the coal (or rock) is extracted it can betransported from the continuous miner 146 to the conveyor belt usingmotorized haulers (not shown). As a result, the conveyor 148 is kept inrelatively close proximity to the face of the mine so that as coal isextracted it needs to be transported by a hauler only a short distancebefore being loaded onto the conveyor belt. Stoppings 150 and curtains152 are also installed in the set of perimeter wall entries 162 todirect air flow.

FIGS. 7 and 7A show a mine ventilation system of another configurationwherein two continuous miners 146 can operate or other mining operationscan be performed in the same set of perimeter wall entries 162 whilemaking the perimeter cuts 144 into the sidewalls 170 or end walls 172 ofthe set of perimeter wall entries. As illustrated in FIG. 7, intake airis directed using stoppings 150 through the main entries 114, throughthe panel entries 124 and into one of the sets of perimeter wall entries162 so that the intake air passes the face of the mine. As shown,stoppings 150 are located in the set of perimeter wall entries 164 towhich intake air is directed.

Perimeter cuts 144 can be made within one set of perimeter wall entries162 using the two continuous miners 146 as shown in FIGS. 7 and 7B. Theintake air is directed into one of the perimeter wall entries P but issplit to flow through one of the perimeter wall crosscuts 166 before itpasses any of the continuous miners 146 so that intake air is suppliedto the opposing perimeter wall entry M. Thus, intake air is supplied toboth continuous miners 146 while making cuts 144 into opposite sidewalls170 of the perimeter wall entries 162. The intake air is directed pastboth of the continuous miner 146 (i.e., the face of the mine) therebyentraining any potential harmful gases or dust. After passing thecontinuous miner 146 in perimeter entry P, the return air, is directedout of the set of perimeter wall entries 162 through the bleed pathway154 to one or more previously mined sets of perimeter wall entries. Theintake air diverted through the perimeter wall crosscut 166 past thecontinuous miner 146 in perimeter entry M and is exhausted through twoof the panel entries A, B. The return air then flows through the mainentries 114 to the vent location (not shown) located outside of themine.

The perimeter cuts 144 along the sidewalls 170 of set of perimeter wallentries 162 are made starting with the cut nearest the end wall 172 andworking toward the set of panel entries 122. The cuts 144 in the endwall 172 are made before the cuts in the sidewall 170. As the continuousminers 146 work their way toward the set of panel entries 122, thestoppings 150, curtains 152, and/or conveyor belt 148 are disassembledin advance of the continuous miners so that the stoppings, curtains, andconveyor belt do not interfere with the mining process and to ensureproper air flow at the face of the mine.

As shown in FIG. 7A, roof bolts 120 are not used within the cut 144. Inthe configuration illustrated in FIG. 7, approximately 30 percent of thecoal mined from within the set of perimeter wall entries 162 having fourperimeter wall entries 164 is done so from unbolted portions of themine. The percentage of unbolted area within the set of perimeter wallentries 162 can be increased by advancing fewer perimeter wall entries164 per set. For example, in the set of perimeter wall entries 162having three perimeter wall entries 164, the unbolted area of the set ofrooms increases to about 37 percent. In the set of perimeter wallentries 162 with only two perimeter wall entries 164, the area of theset of perimeter wall entries that is mined and unbolted isapproximately 48 percent. Accordingly, mining operations havingperimeter cuts 144 is significantly more economical than miningoperations without cuts. Moreover, the greater the distance of theperimeter wall entries 164 the greater number of perimeter cuts 144 thatcan be made in the set of perimeter wall entries.

FIGS. 8 and 8A show a ventilation system having yet anotherconfiguration wherein two continuous miners 146 can be used to makeperimeter cuts 144 within adjacent sets of perimeter wall entries 162 onthe same side of the panel development 110. Intake air is directed usingboth stoppings 150 and curtains 152 to flow through the main entries114, through three of the panel entries E, F, G and through one of thepanel crosscuts 126. The intake air is split into two flow paths in oneof the exterior panel entries A and is directed into two adjacent setsof perimeter wall entries 162. The intake air is directed so that atleast two of the perimeter wall entries J, L, M, P within each of thetwo sets of perimeter wall entries 164 have intake air flowing throughthem in the same direction. As a result, the intake air entrains andcarries away any potential harmful gases or dust generated by the twocontinuous miners 146. It is understood that each of the sets ofperimeter wall entries 162 could have two continuous miners 146 (for atotal of four continuous miners) as shown in FIG. 7. It is alsounderstood the intake could be split so that it supplies intake air tosets of perimeter wall entries 162 on opposite sides of set of panelentries 122 as shown in FIG. 5 to allow up to eight continuous miners146 to be used within the same panel development 110.

After passing the face of the mine, the return air, is directed out ofeach set of perimeter wall entries 162 through the bleed pathway 154 toone or more of the previously mined sets of perimeter wall entries 162.The return air flows out of the previously mined set(s) of perimeterwall entries 162, through two panel entries A, B and through the set ofmain entries 112 to the vent location located outside of the mine.

FIGS. 9, 9A, 10, and 10A show a method of mining that allow twocontinuous miners 146 to be operated simultaneously during thedevelopment of the panel development 110. In this method, one of thecontinuous miners 146 is used to advance the set of panel entries 122off of the set of main entries 112. Once the continuous miner 146advances the set of panel entries 122 far enough away from the set ofmain entries 112, the other continuous miner 146 can be used to advancethe sets of perimeter wall entries 162. For example, as shown in FIGS. 9and 9A, one of the continuous miners 146 was used to advance the setpanel entries 122 to approximately half of its intended depth, and theother continuous miner 146 was used to advance the first three perimeterwall entries 162 on the left side of the set of panel entries 122. Morespecifically, FIGS. 9 and 9A show one of the continuous miner 146 beingused to make perimeter cuts 144 within one of the sets of perimeter wallentries 162 while the other continuous miner 146 is being used toadvance the set of panel entries 122. The two continuous miners 146 canbe operated simultaneously.

In this configuration, intake air is directed using both stoppings 150and curtains 152 to flow through the main entries 114, through two ofthe panel entries E, F and through one of the panel crosscuts 126. Theintake air is split into two flow paths in one of the exterior panelentries A. One of the intake air flow paths is directed into one of thesets of perimeter wall entries 162. The intake air is directed so thatit passes the continuous miner 146 to entrain and carry away anypotential harmful gases or dust generated by the continuous miner 146.The intake air is directed to flow through at least one of the perimeterwall entries P. It is understood that two continuous miners 146, asshown in FIGS. 7 and 7A, could be used to make the perimeter cuts 144.After passing the continuous miner 146, the return air is directed outof the set of perimeter wall entries 162 through the bleed pathway 154to one or more of the previously mined sets of perimeter wall entries162. The return air flows out of the previously mined set(s) ofperimeter wall entries 162, through two panel entries A, B and throughthe set of main entries 112 to the vent location located outside of themine.

The other intake air split is directed through one of the panel entriesA to the leading panel crosscut 126 where it can pass the othercontinuous miner 164 that is being used to advance the set of panelentries 122. After the intake air passes the continuous miner 146 itentrains and carries away any potential harmful gases or dust generatedby the continuous miner. The return air is directed out of the set ofpanel entries 122 through one of the exterior panel entries G. Thereturn air flows out of panel entry G through the set of main entries112 to the vent location located outside of the mine.

As the set of panel entries 122 is advanced, the conveyor belt 148 isextended further into the set of panel entries so that the conveyor 148is kept in relatively close proximity to the face of the mine. Thus, ascoal is extracted it needs to be transported by a hauler only a shortdistance before being loaded onto the conveyor belt 148. Additionalstoppings 150 and/or curtains 152 are also installed in the set of panelentries 122 to maintain the desired air flow.

After the sets of perimeter wall entries 162 on the left side of thepanel development 110 and the set of panel entries 122 have been fullyadvanced, the sets of perimeter wall entries on the right side of thepanel development (as viewed in FIG. 10) are mined in a retreatingfashion. That is, the sets of perimeter wall entries 162 are minedstarting with the set of perimeter wall entries located farthest fromthe set of main entries 112 and working sequentially toward to the setof main entries. As the sets of perimeter wall entries 162 arecompleted, the conveyor belt 148 is disassembled. Moreover, thestoppings 150 and/or curtains 152 are moved or disassembled as necessaryto maintain the desired air flow through the panel development 110.

FIGS. 10 and 10A illustrate a method of mining the sets of perimeterwall entries 162 on the right side of the panel development 110. In thisconfiguration, two continuous miners 146 are being used to makeperimeter cuts 144 within adjacent sets of perimeter wall entries 162 onthe same side of the panel development 110. It is understood that thetwo continuous miners 146 can be used simultaneously to advanceperimeter wall entries 164 and perimeter wall crosscuts 166 in adjacentsets of perimeter wall entries 162. In the illustrated configuration,intake air is directed using both stoppings 150 and curtains 152 to flowthrough the main entries 114, through two of the panel entries E, F andthrough one of the panel crosscuts 126. The intake air is split into twoflow paths in one of the exterior panel entries G and is directed intotwo adjacent sets of perimeter wall entries 162. The intake air isdirected so that at least one of the perimeter wall entries 164 withineach of the two sets of perimeter wall entries 162 have intake airflowing through them in the same direction. In the illustratedconfiguration, the intake air is directed into all four of the perimeterwall entries 162 in each of the two sets of perimeter wall entries 164.As a result, the intake air entrains and carries away any potentialharmful gases or dust generated by the two continuous miners 146. It isunderstood that each of the sets of perimeter wall entries 162 couldhave two continuous miners 146 (for a total of four continuous miners)as shown in FIG. 7 for making the perimeter cuts 144.

After passing the continuous miners 146, the return air, is directed outof each set of perimeter wall entries 162 through the bleed pathway 154toward the previously mined sets of perimeter wall entries 162. In otherwords, the return air is directed away from the set of main entries 112.The return air flows out of the previously mined set(s) of perimeterwall entries 162, through at least one panel crosscut 126 and into oneof the sets of perimeter wall entries 162 on the opposite side (i.e.,the left side) of the panel development 110. The return is furtherdirected through the bleed pathway 154, through the set of perimeterwall entries 162 nearest the set of main entries 112, through two of thepanel entries A, B, and through the set of main entries 112 to the ventlocation located outside of the mine.

It is understood that some or all of the perimeter wall pillars 138, thepanel pillars 128, and/or the main pillars 118 may be extracted (oftencalled “pillaring”) causing the overlying surface to subside, or may beleft in place as a permanent support for the overlying surface.

Having described the invention in detail, it will be apparent thatmodifications and variations are possible without departing from thescope of the invention defined in the appended claims.

When introducing elements of the present invention or the preferredembodiments(s) thereof, the articles “a”, “an”, “the” and “said” areintended to mean that there are one or more of the elements. The terms“comprising”, “including” and “having” are intended to be inclusive andmean that there may be additional elements other than the listedelements.

In view of the above, it will be seen that the several objects of theinvention are achieved and other advantageous results attained.

As various changes could be made in the above methods without departingfrom the scope of the invention, it is intended that all mattercontained in the above description and shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

1. A method of underground mining comprising: mining material using acontinuous miner to form at least one set of entries comprising aplurality of entries, a plurality of crosscuts extending between andconnecting the entries, and a plurality of pillars being defined by theentries and crosscuts, the entries and crosscuts defining a passagehaving a roof, a floor, and sidewalls, the pillars at least in partbeing adapted to prevent the roof of the passage from collapsing;installing roof bolts in the roof of the passage; and mining materialfrom the sidewalls of the passage with the continuous miner to formperimeter cuts extending outwardly from the passage, the perimeter cutsbeing free of roof bolts, at least approximately 30 percent of thematerial mined from within the set of entries being derived from theunbolted perimeter cuts.
 2. A method as set forth in claim 1 whereinmaterial is mined to form at least one set of perimeter wall entriescomprising a plurality of perimeter wall entries, a plurality ofperimeter wall crosscuts, and a plurality of perimeter wall pillars. 3.A method as set forth in claim 2 wherein material is mined to form fourperimeter wall entries.
 4. A method as set forth in claim 2 whereinmaterial is mined to form three perimeter wall entries.
 5. A method asset forth in claim 2 wherein material is mined to form two perimeterwall entries.
 6. A method as set forth in claim 2 wherein at leastapproximately 37 percent of the material mined from the set perimeterwall entries is derived from the unbolted perimeter cuts.
 7. A method asset forth in claim 2 wherein at least approximately 48 percent of thematerial mined from the set perimeter wall entries is derived from theunbolted perimeter cuts.
 8. A method as set forth in claim 1 wherein theentries are formed to have a length greater than 600 feet.
 9. A methodas set forth in claim 1 wherein a plurality of continuous miners isoperated in the set of entries to form the perimeter cuts.
 10. A methodas set forth in claim 9 wherein two continuous miners are operated inthe set of entries.
 11. A method as set forth in claim 1 furthercomprising installing stoppings in the crosscuts to direct ventilationair to flow in two separate streams through the set of entries.
 12. Amethod as set forth in claim 1 further comprising conveying the minedmaterial out of the set of entries using a conveyor belt.